The present invention relates to a brake master cylinder comprising housing having a longitudinal bore with a pressure chamber and an associated pressure piston; a transverse bore to house a pressure control device, the transverse bore having a stepped piston and a valve controlled thereby; a mounting flange adjacent one end of the longitudinal bore; and a reservoir arranged above the longitudinal bore.
A brake master cylinder of this type is known, for example, from British Pat. No. 1,030,781, whose housing has a first outlet socket for the connection of a brake line leading to the front wheel cylinders, the first outlet socket being located at the end of the longitudinal bore which faces the mounting flange. Above the longitudinal bore, on the side of the reservoir which is facing the mounting flange, a transverse bore is provided to house the pressure control device, the axis of which transverse bore extends vertically and intersects the axis of the longitudinal bore. At the upper end of this transverse bore, there is a second outlet socket for connecting a brake line which leads to the rear wheel cylinders. By placing the assembly of the pressure control device in the housing of the master cylinder, this construction has the advantage of not needing any connection line between the master cylinder and the pressure control device. Thus, it will not be necessary to provide any special assembly space, or any means for fastening the pressure control device to the vehicle. This will facilitate assembly.
Further, a tandem master cylinder is known (Teves "Bremsen-Handbuch"-Teves Brake Handbook-1977; page 45) wherein the longitudinal bore has two pressure chambers each associated with a different one of two pressure pistons each of which are associated with a different one of two brake circuits and wherein two parallel inlet sockets each connect a different one of the two pressure chambers with the mounted reservoir. In this arrangement, the reservoir virtually extends over the entire length of the longitudinal bore. If a pressure control device is to be used with this tandem master cylinder, the pressure control device will have to be mounted separately with respect to the tandem master cylinder.